Described is a method for a digital system having a multiplicity of self-calibrating interfaces for synchronizing multiple elastic interface buses into the same target cycle, particularly for an SMP environment, which allowing the multiple elastic interface buses to take advantage of minimized latency in the cases where their data all arrive early and also described is an apparatus for implementing the method. To achieve this, the invention includes the steps of:                sending a synchronization pattern through each of the multiple buses of the elastic interface;        determining a target cycle for the elastic bus having the latest arriving elastic interface data arrival; and        applying this target cycle to all the interfaces.        
This allows the use of automatic alignment elastic interfaces with automatic receiver target cycle calculation and minimized latency, providing the ability to calibrate for wide range of voltages, temperature, and cycle times while also supporting synchronous interfaces.
In particular, the described digital system method for a multiplicity of self-calibrating interfaces synchronizes all the received data, even if portions of the synchronous data were sent over different elastic interface buses and arrive with different cycle latencies.
Disclosed is also a method for determining the latest arriving elastic interface data signal as well as a method for calculating the corresponding target cycle parameter to allow for ALL the interfaces to align their data to this latest arriving interface data signal, while still maintaining the earliest arrival cycle for the complete data to minimize system latency.
Finally, a method is described to test the resulting interface to ensure that the interface is aligned properly.
The receiver interfaces may be elastic interfaces or not. The multiplicity of elastic interface receivers may be on the same chip or on multiple chips. The arbitration logic may be on one chip or across multiple chips as well.
These and other improvements are set forth in the following detailed description. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.
Our detailed description explains the preferred embodiments of our invention, together with advantages and features, by way of example, with reference to the drawings.